Final answer:
The protein portion providing structural integrity and receptor recognition in a lipoprotein particle is known as an apolipoprotein. These proteins are key components in the transport of lipids through the bloodstream and play roles in the metabolism and function of lipoproteins such as chylomicrons, HDL, and LDL.
Step-by-step explanation:
The protein portion of the lipoprotein that provides structural integrity and allows for receptors to recognize the lipoprotein particle is called an apolipoprotein. Apolipoproteins play a critical role in the structure, function, and metabolism of lipoproteins. They are essential for the transport of lipids through the blood, as they combine with lipids to form different types of lipoproteins, such as high-density lipoproteins (HDL), low-density lipoproteins (LDL), and chylomicrons. These lipoproteins differ by their density, composition, and the specific transport functions they serve in lipid metabolism. For instance, HDL is involved in the reverse transport of cholesterol from tissues to the liver, often referred to as 'good cholesterol', while LDL is known for transporting cholesterol to peripheral tissues and is associated with an increased risk of atherosclerosis.